Finn Bradyis Cheryl Masters's long lost son, Gemma Masters's half-brother and John Constantine's apparent nephew from Ireland. First appearing in Hellblazer issue 293, it was found out that Cheryl once got pregnant as a teen, during which her father Thomas cast away the child into an orphanage.
Finn grew up a normal life until the "Curse of the Constantine's" struck him, during which he began enamored in magic, and he himself was framed as a serial killer who's been killing a number of people in Ireland. The serial killer was also a mage who was a big fan of John Constantine. John on the other hand, tracked down Finn in order to finally cleanse his sister's sin and take her soul away from Hell. John defeats the serial killer and succeeds.
Finn was also present during John Constantine's funeral, where he showed that he has gotten interested in magic. He once saved Epiphany when she was attacked by a disguised Julian, and the two started a relationship which John actually approves.